Empirical Characterization of Cable Effects on a Reference Lightning Impulse Voltage Divider

The effect of measurement cables on impulse voltage measurement system signal transmission has been widely ignored by the high-voltage community. During the last years, the cable length effects have been reported, but the results have not been fully consistent. This article characterizes cable effects on a resistive impulse voltage divider system using three different empirical test methods. The used methods are step response analysis using convolution, low-voltage analysis with an impulse calibrator, and high-voltage impulse analysis with an impulse generator. Results show that with reasonable cable lengths up to 25 m, the time parameter errors increase almost linearly with the cable length. The tested divider system was not sensitive to the tolerance of the 50 Ω termination at the cable end. The cable effect seems to be related to the current flowing through the cable, and the related errors can be reduced using a high-impedance termination at the digitizer end of the cable. Either short cable or high-impedance termination at the digitizer end is recommended for this type of divider. In addition, the results show that the three applied methods produce comparable results.